The present invention relates to test adapters, and more particularly to test adapters for the dynamic testing of printed circuit boards.
Most electrical and electronic systems typically comprise a set of closely stacked printed circuit boards fitted vertically into backplanes or card cage areas. Performing dynamic maintenance or testing functions on these cards, sometimes referred to as xe2x80x9chot testingxe2x80x9d, can be very difficult due to the presence of adjacent cards on either side of the card under test having very tight clearances between the adjacent cards.
To aid in testing or maintenance of printed circuit boards, test adapters commonly referred to as xe2x80x9cextender cardsxe2x80x9d are used. Extender cards typically comprise a unitary card portion that is substantially the same size as the board under test, having electrical connectors on opposite edges that are connected in a xe2x80x9cstraight acrossxe2x80x9d manner. Extender cards also typically comprise card guides attached to the rear upper and lower edges of the unitary card portion.
The card under test is removed from the backplane and the front of the extender card opposite the card guides is plugged into the backplane in its place. The extender card carries all of the appropriate connections from the backplane to the extender card""s rear edge where the rear connector is available, and the card under test is plugged into the rear connector via the card guides. With the extender card plugged into the backplane and the card under test inserted into the extender card, the card under test is available with both sides open to a craftsperson wishing to work on the card.
In general, the extender card has no active components to provide processing or programming capabilities, and serves simply to provide more convenient access to a circuit card. Special purpose extender cards may provide processing or programming capabilities.
Typically, when a circuit card is plugged into a backplane, mechanical assists, usually in the form of ejector levers on the card, assist in the insertion and removal of the card from the backplane connector. In use, the ejector levers on the cards mate with ejector lever brackets on the card cage or module. The ejector levers allow the craftsperson to easily and smoothly overcome the retention and insertion forces on card removal and insertion, even though these forces can be quite large for, for example, a large format 330 or 440 pin card. Use of the ejector levers also allows the circuit cards to be inserted and removed straight in and straight out, which eliminates damage to the circuit card, the circuit card pins and the backplane connector pins that may be caused by, for example, rocking the card back and forth on insertion or removal.
While circuit cards, particularly large format circuit cards, typically have ejector levers to assist in the insertion and removal of the card into and out of the backplane, extender cards do not. The extender cards are manually inserted with no mechanical assists, which can cause damage to the extender card, the extender card pins, and the backplane connector pins. U.S. Pat. No. 3,958,858 even teaches to use the card guides on the extender card to insert the extender card into the backplane, which can lead to additional damage to the extender card and card guides.
The typical extender card also does not have ejector lever brackets on the card guides to allow for the use of ejector levers on circuit cards under test during the insertion and removal of the circuit card into and from the extender card. This can cause damage to the circuit card, the extender card and the card guides.
Accordingly, it is an object of the present invention to provide an extender card having ejector levers and ejector lever brackets in a manner that will eliminate damage to the extender card and the circuit card under test due to the insertion and removal of the extender card into and from the backplane, and the circuit card into and from the extender card.
The present invention is an extender card arrangement having ejector levers attached to the unitary card portion of the extender card to aid in the insertion and removal of the extender card into and from the backplane, and having ejector lever brackets attached to the extender card card guides to allow the ejector levers on the card under test to be used to aid in the insertion and removal of the card under test into and from the extender card.